(1) Field of the Invention
This invention is directed to hand tools for use in the insertion of conductors in solderless connectors and especially to tools for use in the installation of individual conductors of communications cables in connectors extending from terminal blocks. More particularly, the present invention relates to the establishment of solderless connections between electrical conductors, particularly insulated conductors, and closely spaced connectors in communications systems. Accordingly, the general objects of the present invention are to provide novel and improved tools and methods of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use with the multiple electrical connector of co-pending application Ser. No. 184,665, filed Sept. 8, 1980. Co-pending application Ser. No. 184,665, Sept. 8, 1980 which is assigned to the assignee of the present invention, is hereby incorporated herein by reference.
The present invention has been found to be particularly useful in the communications field and especially in the art of telephony. It is common, in the installation of a telephone system, for multiple conductor telephone cables to be terminated at a mounting block which has a plurality of solderless connectors extending outwardly therefrom. The cable conductors are inserted in connectors, typically between a pair of opposed fingers, in such a manner as to establish electrical connection without resort to bonding techniques such as soldering. The connectors, and particularly the opposed fingers or other elements between which each of the cable conductors is inserted, are designed such that any insulation on the conductor is removed therefrom as the conductor is forced between the opposing elements of the connector.
In the prior art, wherein the opposing contact elements of the connectors were formed flat stock, wire installing tools of the type disclosed in U.S. Pat. No. 4,194,256 have been designed for use by the technician. These prior wire installing tools, however, cannot be employed in the insertion of electrical conductors in the connectors of a multiple connector assembly of the type disclosed in referenced application Ser. No. 184,665. To be more specific, referring to prior art "flat" connectors of the type known in the art as the "66 Type", which are shown in U.S. Pat. No. 3,112,147, the installing tool must be provided with an internal cavity which functions to hold the fingers or beams of the connector together as a conductor is forced therebetween. If too much spreading of the connector fingers is permitted, the fingers typically being comprised of copper alloys, the material will undergo cold flow in the base regions of the fingers and there will be insufficient force applied to the conductor to insure its permanent capture between the fingers. The connectors of application Ser. No. 184,665 are defined by high strength coil segments. As a conductor is forced between a pair of these opposed coil segments, the forces imposed on the outermost portions of the connector are high while those at the bottom of the cooperating elements or segments remain low. This is precisely the opposite to what occurs in a "66 Type" connector. Accordingly, there is no danger of cold flow of the copper wire which defines the connector segments. Thus, a tool cavity to prevent excessive spreading of the fingers of the connector is not required.
A further disadvantage of prior art wire installing tools of the type disclosed in U.S. Pat. No. 4,194,256 resides in the fact that, because the conductor being inserted must span the internal cavity or chamber in the tool stem which receives the connector fingers, the installing tool cannot be used with stranded wire. As is well known, stranded wire has minimal flexural strength and the wire will inherently be bent in the portion which is in registration with the tool cavity. Thus, in the prior art, solid wire must be used with 66 Type connectors.
It is also to be noted that with very compliant wire, particularly stranded wire, spreading apart of the connector fingers as the wire is inserted therebetween may result in a failure of the insulation to be stripped from the wire. Thus a simple blade-type tool could not successfully be employed to insert stranded wire in a connector of the type shown in application Ser. No. 184,665.
A further deficiency of prior art wire installing tools resides in the fact that the minimum dimensions of the stem portions of such tools are comparatively large and, of course, the present tendency is for increasingly high connector density. Even if the prior art tools could be modified for use with connectors of the type disclosed in application Ser. No. 184,665, the working portion of the tools, the tool of U.S. Pat. No. 4,194,256 for example, would be too large to be of practical use.